No abstract

The mechanism of neurological disturbances in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is controversial. We studied 12 patients with MELAS using conventional and diffusion weighted MRI (DWI) and MR spectroscopy (MRS), to look at the physiopathology of the stroke-like events. Although conventional MRI showed lesions in all patients, DWI was more sensitive. One patient did not show high signal on DWI 48 h after a from stroke-like episode, but MRS demonstrated a lactate peak in left occipital lobe; 2 weeks after the attack, high signal was demonstrated on the right frontal lobe where MRS had shown a lactate peak. Our findings suggest a possible predictive ability of (1)H-MRS, in showing early MELAS lesions and supports the hypothesis that mitochondrial metabolic dysfunction may precedes abnormalities on DWI.

No abstract

Patients with multiple system atrophy (MSA) may show the "cross" sign in the pontine base that has been considered as an expression of the degeneration of pontine neurons and transverse pontocerebellar fibers. However, correlations between pontine base atrophy and existence of "cross" sign have not been fully investigated. The authors studied 68 patients with MSA (47 MSA-C [predominantly cerebellar ataxia], 21 MSA-P [predominantly parkinsonism], mean [+/-SD ] 58.7 +/- 10.9 years). T1-weighted (T1W) sagittal and axial images and T2-weighted (T2W) axial images were obtained for all patients and controls. To measure the areas of pontine basis and cerebellar vermis, the authors used midsagittal T1W images and analyzed a bit map transformed on a computer. They classified atrophy in the pontine base into 3 grades. There is significant correlation between atrophies of pontine base and existence of the cross sign. All patients with a smaller area of pontine base 2 standard deviations below those of normal controls had the cross sign. This supports that existence of the cross sign depends only on the extent of pontine base atrophies.

A 63-year-old man admitted a hospital because of headache. He had pain almost all day long, especially when he touched his head. A magnetic resonance image (left) was taken but no abnormality was found. The patient admitted our hospital for further examination. The magnetic resonance image taken by former hospital demonstrated an abnormal intensity in the fatty tissue in the skull (arrowheads). Subsequent bone image CT (right) at our hospital showed multiple osteolytic lesions in the skull. He was diagnosed as multiple myeloma.MRI is an outstanding tool and physicians are tends to order MRIs without taking conventional radiographs. However, bone is a weak point for MRI.